This invention relates to a method and apparatus for fabricating a spiral pipe. A method and apparatus for making a spiral pipe are known from U.S. Pat. No. 2,505,623. Spiral pipes with a slight curvature and/or moderate quality requirements can be fabricated by the known method and the associated apparatus. However, the known method fails for requirements that extend beyond this.
In actual practice, however, spiral pipes are frequently used for tasks which require stronger deformations and thus a high quality with regard to dimensional accuracy as well as with regard to the material structure, for example, as eccentric spirals for eccentric spiral pumps, as drive elements for well-drilling devices, and as elements for propeller pumps and propeller motors. Up to now, eccentric worms or screws, if they have not been turned or spun from solid material, have been welded together from sheet-metal half-shells, the shape of which is very complicated, or formed by repeatedly pressing and withdrawing a pipe into and from a conical die with flexibly mounted die parts.